Display device with coordinate input function

ABSTRACT

A display device with coordinate input function with transparent electrodes for inputting coordinates disposed in an X-Y matrix form on an optical phase compensation cell, such as an optically anisotropic phase compensation film, provided for a liquid crystal display panel of two-layer type. Coordinate input can be performed even in the case of a liquid crystal display panel divided into two, upper and lower, separately driven parts to increase the resolution of the display screen, because of the transparent electrodes disposed on the optical phase compensation cell.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.07/516,550, filed Apr. 30, 1990 and now U.S. Pat. No. 5,162,782.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device with coordinate inputfunction by which a man-machine interface is achieved between anelectronic computer and its operator.

2. Description of the Prior Art

In the prior art, a liquid crystal display device with coordinate inputfunction is disclosed, for example, in Japanese patent applicationlaid-open No. 262835/1986 or Japanese patent application laid-open No.81521/1988.

FIG. 1 is a constitution diagram of a display device with a coordinateinput function in an example of the prior art. Also, FIG. 2 is asectional view of a liquid crystal display cell.

In FIGS. 1 and 2, reference numeral 1 designates a liquid crystaldisplay cell where a liquid crystal 10 is sealed between two glasssubstrates 12, 13, numerals 2 and 3 designate transparent electrodesarranged at a predetermined distance on the glass substrates 12, 13,numerals 4 and 5 designate drive circuits to activate the transparentelectrodes 2, 3, numeral 6 designates a control circuit, numeral 7designates a magnetic field sensor, numeral 8 designates an amplifier toamplify output signals of the magnetic field sensor 7, numeral 11designates a seal substance to seal the liquid crystal 10 between theglass substrates 12, 13, and numerals 14 and 15 designate polarizingplates.

Next, the operation of this arrangement will be described.

The control circuit 6 supplies an AC signal as a coordinate inputdetection signal in time-sharing with a display drive signal through thedrive circuits 4, 5 in sequence to the transparent electrodes 2, 3arranged on the glass substrates 12, 13 of the liquid crystal displaycell 1. As a result, a rotating magnetic field is generated on theperiphery of each of the transparent electrodes 2, 3 by the coordinateinput detection signal current. If the sensor 7 with a material havingelectromagnetic induction effect characteristics embedded therein comesclose to the field, a detection voltage corresponding to the rotatingmagnetic field is obtained from the sensor 7. The detection voltage isamplified by the amplifier 8 to a suitable amplitude and then comparedin sequence in synchronism with timing of the coordinate input detectionsignal applied to the transparent electrodes 2, 3, thereby anintersection position of the transparent electrodes 2 and 3 can bedetected.

The display device with a coordinate input function of theabove-mentioned constitution is advantageous in that display of theimage and the coordinate input can be realized by the same transparentelectrodes 2, 3 and a special coordinate input panel is not required.

Since the display device with coordinate input function in the prior artis constituted as above described and the coordinate input detectionsignal current flows through the transparent electrodes, basically, thetransparent electrodes 2, 3 must not have a nonconductive part therealong. However, liquid-crystal display devices in recent years arecalled upon to have higher resolution, and in order to preventdeterioration in the contrast ratio of the display image, a liquidcrystal display panel having a display screen divided into two, upperand lower, separately driven parts is used. Liquid crystal displaypanels are being significantly advanced, and a liquid crystal displaypanel of two-layer type to enable the black-and-white display has beenput to practical use in recent years and also a color liquid crystaldisplay panel in combination of the liquid crystal display panel oftwo-layer type with a color filter has been developed.

FIG. 3 is a sectional view of a standard liquid crystal display panel oftwo-layer type in the prior art, and FIG. 4 is a constitution diagram ofa liquid crystal display panel divided into two, upper and lower,separately driven parts in the prior art. In FIGS. 3 and 4, referencenumeral 1 designates a liquid crystal display cell, numerals 2U, 2L and3 designate transparent electrodes, numerals 4U, 4L and 5 designatedrive circuits, numeral 6 designates a control circuit, and numeral 21designates a liquid crystal cell for phase compensation, which isconstituted by sealing a liquid crystal 10 between glass substrates 32and 33 with a seal substance 31 and compensates optical characteristicsof the liquid crystal display panel 1. Since details of the principle orthe like of the liquid crystal panel of two-layer type shown in FIG. 3do not have direct relation to the present invention, the descriptionshall be omitted here.

As clearly seen from FIG. 4, each of the transparent electrodes arrangedin the vertical direction is divided into an upper transparent electrode2U and a lower transparent electrode 2L corresponding to the dividing ofthe display screen. In this case, the bottom end of the uppertransparent electrode 2U and the top end of the lower transparentelectrode 2L are within the liquid crystal display cell 1 and thereforecannot be drawn as electrodes outside the liquid crystal cell 1.Accordingly, the coordinate input detection signal current cannot flowthrough the transparent electrodes 2U, 2L, and the display device withcoordinate input function as shown in FIG. 1 cannot be constituted as inthe prior art.

FIG. 7 is a sectional view of a standard liquid crystal display panel oftwo-layer type with an optical phase compensation film in the prior art.In FIG. 7, reference numeral 1 designates a liquid crystal display cell,numerals 2U, 2L and 3 designate transparent electrodes, and numeral 41designates a phase compensation film which exhibits optical anisotropyused for optical phase compensation, which compensates opticalcharacteristics of the liquid crystal display panel 1. Since details ofthe principle or the like of the liquid crystal panel of two-layer typeshown in FIG. 7 do not have direct relation to the present invention,the description shall be omitted here.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problems in the prior art, anobject of the present invention is to provide a display device with acoordinate input function even in case of a liquid crystal display panelhaving a display screen divided into two, upper and lower, parts to bedriven separately, by ensuring the continuity of the coordinate inputdetection signal current flowing in a two-layer type liquid crystaldisplay panel.

In order to attain the foregoing object, in a display device withcoordinate input function according to the present invention, a liquidcrystal display panel of the two-layer type with a liquid crystal cellfor phase compensation is used, and coordinate input electrodes arearranged in the liquid crystal cell for phase compensation and thecoordinate input detection signal current flows through the coordinateinput electrodes whereby inputting of the coordinates is performed.

In order to further attain the foregoing object, in a display devicewith coordinate input function according to the present invention, aliquid crystal display panel of the two-layer type is used, with anoptically anisotropic film layer for optical phase compensation, andcoordinate input electrodes are arranged on the optically anisotropicphase compensation film, and the coordinate input detection signalcurrent flows through the coordinate input electrodes whereby inputtingof the coordinates is performed.

The foregoing and other objects and novel features of the presentinvention will be more fully appear from the following detaileddescription when the same is read in connection with the accompanyingdrawings. It is to be expressly understood, however, that the drawingsare for the purpose of illustration only and are not intended as adefinition of the limits of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a constitution diagram of a display device with coordinateinput function in the prior art;

FIG. 2 is a sectional view of a liquid crystal display panel in theprior art;

FIG. 3 is a sectional view of a standard liquid crystal display panel oftwo-layer type in the prior art;

FIG. 4 is a constitution diagram of a liquid crystal display paneldivided into two, upper and lower, parts in the prior art;

FIG. 5 is a constitution diagram of a display device with coordinateinput function according to an embodiment of the present invention;

FIG. 6 is a sectional view of a liquid crystal display panel oftwo-layer type according to the embodiment of the present invention ofFIG. 5;

FIG. 7 is a sectional view of a standard liquid crystal display panel oftwo-layer type with an optical phase compensation film in the prior art;

FIG. 8 is a constitution diagram of a display device with coordinateinput function with an optical phase compensation film according toanother embodiment of the present invention;

FIG. 9 is a sectional view of a liquid crystal display panel oftwo-layer type according to the embodiment of the present invention ofFIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described referring tothe accompanying drawings.

FIG. 5 is a constitution diagram of a display device with coordinateinput function as an embodiment of the present invention. In FIG. 5,reference numeral 1 designates a liquid crystal display cell, numerals2U, 2L, 3 designate transparent electrodes for image display, which arearranged on glass substrates 12, 13 (FIG. 6) to constitute the liquidcrystal display cell 1, numerals 4U, 4L, 5 designate drive circuitswhich activate the transparent electrodes 2U, 2L, 3 and drive the liquidcrystal display cell 1, numeral 6 designates a control circuit, numeral7 designates a magnetic field sensor, and numeral 8 designates anamplifier which amplifies output signals of the magnetic field sensor 7.Also, numeral 21 designates a liquid crystal cell for phasecompensation, numerals 22, 23 designate transparent electrodes forcoordinate input, which are arranged on glass substrates 32, 33 toconstitute the liquid crystal cell 21 for phase compensation, andnumerals 24, 25 designate drive circuits which activate the transparentelectrodes 22, 23 and through which the coordinate input detectionsignal current flows.

FIG. 6 is a sectional view of the liquid crystal display panel as theembodiment of the present invention. In FIG. 6, reference numeral 1designates a liquid crystal display cell, numeral 21 designates a liquidcrystal cell for phase compensation, numerals 11, 31 designate sealsubstances which seal a liquid crystal 10 between glass substrates 12,13 and between glass substrates 32, 33 respectively, and numerals 14, 15designate polarizing plates.

As clearly seen from comparison with FIG. 3 showing a sectional view ofthe standard liquid crystal display panel of two-layer type in the priorart, in the present invention, the glass substrates 32, 33 whichconstitute the liquid crystal cell 21 for phase compensation of theliquid crystal display panel of two-layer type, are provided withtransparent electrodes 22, 23 arranged in an X-Y matrix form, and an ACsignal as the coordinate input detection signal is supplied from thecontrol circuit 6 through the drive circuits 24, 25 to the transparentelectrodes 22, 23 in sequence. As a result, a rotating magnetic field isgenerated on the periphery of each of the transparent electrodes 22, 23by the coordinate input detection signal current. And then, thecoordinate input can be detected through processes similar to those inthe prior art. Thus, even in a liquid crystal display panel having adisplay screen divided into two, upper and lower, parts which areseparately driven, the coordinate input detection can be performed.

The liquid crystal cell for phase compensation 21 is an example of acompensation cell to improve the optical characteristics of the liquidcrystal cell for display 1. Another example of an optical phasecompensation cell to improve the optical characteristics of the liquidcrystal cell for display 1 is an optical phase compensation film or thelike which exhibits optical anisotropy. Substances suitable forcomprising optically anisotropic films include polycarbonates, polyvinylalcohols, polyethylene tetraphthalates, and the like. The thickness ofthe optically anisotropic film can be in the range of between about 50micrometers to about 150 micrometers. Preferably, the thickness of theoptically anisotropic film is about 100 micrometers. Generally, a filmcomprised of a suitable substance possesses the property of opticalanisotropy, characterized by a position dependent and spatially varyingindex of refraction, when the film is drawn or stretched along an axisof optical activity.

FIG. 8 is a constitution diagram of a display device with coordinateinput function with an optical phase compensation film according toanother embodiment of the present invention. In FIG. 8, referencenumeral 1 designates a liquid crystal display cell, numerals 2U, 2L, 3designate transparent electrodes for image display, which are arrangedon glass substrates 12, 13 (FIG. 9) to constitute the liquid crystaldisplay cell 1, numerals 4U, 4L, 5 designate drive circuits whichactivate the transparent electrodes 2U, 2L, 3 and drive the liquidcrystal display cell 1, numeral 6 designates a control circuit, numeral7 designates a magnetic field sensor, and numeral 8 designates anamplifier which amplifies output signals of the magnetic field sensor 7.Also, numeral 41 designates a phase compensation film which exhibitsoptical anisotropy used for optical phase compensation, numerals 22, 23designate transparent electrodes for coordinate input, which arearranged on phase compensation film 41 to constitute an optical phasecompensation cell which compensates optical characteristics of theliquid crystal display panel 1, and numerals 24, 25 designate drivecircuits which activate the transparent electrodes 22, 23 and throughwhich the coordinate input detection signal current flows.

FIG. 9 is a sectional view of the liquid crystal display panelembodiment of the present invention shown in FIG. 8. In FIG. 9,reference numeral 1 designates a liquid crystal display cell, numeral 41designates a film which exhibits optical anisotropy used for opticalphase compensation, numeral 11 designates a seal substance which seals aliquid crystal 10 between glass substrates 12, 13 and numerals 14, 15designate polarizing plates.

As clearly seen from comparison with FIG. 7 showing a sectional view ofthe standard liquid crystal display panel of two-layer type with anoptical phase compensation film in the prior art, in the presentinvention, as shown in FIG. 9, the phase compensation film 41 of theliquid crystal display panel of two-layer type is provided withtransparent electrodes 22, 23 arranged in an X-Y matrix form, and an ACsignal as the coordinate input detection signal is supplied from thecontrol circuit 6 through the drive circuits 24, 25 to the transparentelectrodes 22, 23 in sequence. As a result, a rotating magnetic field isgenerated on the periphery of each of the transparent electrodes 22, 23by the coordinate input detection signal current. And then, thecoordinate input can be detected through processes similar to those inthe prior art. Thus, even in a liquid crystal display panel having adisplay screen divided into two, upper and lower, parts which areseparately driven, the coordinate input detection can be performed.

Although an electromagnetic coupling system is used as a coordinateinput detection system in the above-described embodiments, the presentinvention is not limited to this.

According to the above-described present invention, the optical phasecompensation cell of the liquid crystal display panel of two-layer typeis provided with transparent electrodes arranged thereon in an X-Ymatrix form as the coordinate input detecting electrodes, whereby thedisplay device with coordinate input function can be constituted withoutusing a special coordinate input panel in addition to the display paneleven in the case that the liquid crystal display panel has a displayscreen that is divided into two parts which are separately driven.

The principles, preferred embodiments and modes of operation of thepresent invention have been described in the foregoing specification.The invention which is intended to be protected heroin, however, is notto be construed as limited to the particular forms disclosed, sincethese are to be regarded as illustrative rather than restrictive.Moreover, variations and changes may be made by those skilled in the artwithout departing from the spirit of the present invention. Therefore,the present invention should not be regarded as being limited to thespecific embodiments disclosed herein, but instead should be regarded asbeing fully commensurate in scope with the following claims.

Furthermore, any element in the following claims expressed as a means orstep for performing a specified function without the recital ofstructure, material, or acts in support thereof shall be construed tocover the corresponding structure, material, or acts described hereinand equivalents thereof.

What is claimed is:
 1. A display device with coordinate input functionhaving a liquid crystal display panel for both displaying images andinputting coordinates, comprising:a sensor means for sensing coordinateinput detection signals from a control means; a liquid crystal displaypanel of two-layer type including an optical phase compensation cell, asa first layer of the liquid crystal display panel and a liquid crystaldisplay cell as a second layer of the liquid crystal display panel; anda plurality of transparent electrodes arranged on said compensation cellin an X-Y matrix form, for inputting the coordinate input detectionsignals to said sensor means, wherein said compensation cell is a phasecompensation film which exhibits optical anisotropy.
 2. The displaydevice with coordinate input function having a liquid crystal displaypanel for both displaying images and inputting coordinates as in claim1, wherein said optically anisotropic phase compensation film comprisesa polycarbonate.
 3. The display device with coordinate input functionhaving a liquid crystal display panel for both displaying images andinputting coordinates as in claim 1, wherein said optically anisotropicphase compensation film comprises a polyvinyl alcohol.
 4. The displaydevice with coordinate input function having a liquid crystal displaypanel for both displaying images and inputting coordinates as in claim1, wherein said optically anisotropic phase compensation film comprisesa polyethylene tetraphthalate.
 5. The display device with coordinateinput function having a liquid crystal display panel for both displayingimages and inputting coordinates as in claim 1, wherein said opticallyanisotropic phase compensation film has a thickness of between about 50micrometers to about 150 micrometers.
 6. The display device withcoordinate input function having a liquid crystal display panel for bothdisplaying images and inputting coordinates as in claim 1, wherein saidoptically anisotropic phase compensation film has a thickness of about100 micrometers.